Device for collecting solar energy

ABSTRACT

A device ( 1, 20, 40 ) for collecting solar energy includes collector elements ( 3 ) and lens elements ( 2 ) for concentrating solar radiation onto the collector elements ( 3 ). The collector elements ( 3 ) are coupled via a conduit for energy transport to an energy processing unit. The lens elements ( 2 ) include at least one lens ( 2 ) which is arranged movably. Drive elements are provided to orient the at least one lens ( 2 ) about at least one orientation axis. The drive elements are provided with a control for the purpose of orienting the at least one lens ( 2 ) in at least substantially continuous and in at least substantially optimal manner relative to an actual position of the sun.

The invention relates to the device for collecting solar energy, comprising collector means and lens means for concentrating solar radiation onto the collector means, wherein the collector means are coupled via a conduit for energy transport to an energy processing unit.

Such a device is known from the international patent application WO 2005/050103. The known device has as lens means a lens assembled from segments. In order to collect solar energy solar radiation captured by the lens is concentrated onto collector means in the form of a spiral-shaped conduit carrying an oil flow. The spiral-shaped conduit will transfer solar heat from the captured solar radiation to the oil flowing therethrough. A thus heated oil is guided through a heat exchanger for the purpose of generating steam therewith which drives a turbine for the purpose of electricity supply. The cooled oil then flows back to the spiral-shaped conduit in a closed circuit in order to be reheated.

Although relatively great power can be generated per se with the known device, the known device has the drawback that the power yield is not constant through the day, even if the solar intensity is.

The invention has for its object, among others, to provide a device of the type stated in the preamble which obviates this drawback to at least significant extent.

A device of the type stated in the preamble has for this purpose the feature according to the invention that the lens means are arranged movably and comprise at least one lens, that drive means are provided to orient the at least one lens about at least one orientation axis and that the drive means comprise a control which is able and adapted to orient the at least one lens in at least substantially continuous and in at least substantially optimal manner relative to an actual position of the sun.

Using the control an orientation of the at least one lens can thus always be set during the course of a day such that solar radiation is incident as perpendicularly as possible on the at least one lens. The energy yield of the device is thus optimized.

A particular embodiment of the device according to the invention has the feature that the conduit comprises a liquid conduit for carrying a liquid therethrough, that the collector means comprise at least a wall part of the liquid conduit, and that the wall part is able and adapted to enter into heat-exchanging contact with the liquid. By concentrating solar radiation on the wall part solar heat will be transferred to a liquid, for instance an oil flow, passing through the liquid conduit. The thus heated liquid can for instance be guided through a heat exchanger for the purpose of generating steam therewith which drives a turbine for the purpose of electricity supply.

A preferred embodiment of the device according to the invention has the feature that the wall part has an at least substantially concave progression. Such a progression of the wall part makes it possible here that, despite the lenses rotating relative to the liquid conduit, foci of the lenses will always be situated on or at the position of the wall part. At any position of the sun solar radiation passing through the lenses will thus be incident upon instead of adjacently of the wall part of the liquid conduit. An energy yield of the device is thus further increased. From an energy viewpoint it is favourable to heat the liquid to the highest possible temperature, since at a higher temperature the heat of the liquid can be more easily converted, whereby higher energy efficiency can be achieved. A further preferred embodiment of the device according to the invention is therefore characterized in that regulating means are provided to regulate a liquid temperature to a value between 400 and 500° C., preferably to about 450° C. A liquid temperature in the stated range has been chosen for practical reasons, for instance in respect of temperature resistance of pipework with fittings.

A further particular embodiment of the device according to the invention has the feature that the conduit comprises a light conductor which is able and adapted to capture and conduct light, wherein a first outer end of the light conductor is coupled to an energy processing unit and the collector means comprise an opposite open outer end of the light conductor. In a practical embodiment hereof the device according to the invention is characterized in that the light conductor comprises at least one fibre, in particular a glass fibre. By concentrating solar radiation onto the open outer end of the fibre sunlight will be captured herein and transported to the energy processing unit. The thus captured sunlight can be processed in the energy processing unit for the purpose of generating energy therefrom.

The advantages of applying a light conductor are also present in a device for collecting solar energy in which the lens means are arranged non-movably, or drive means are provided for the purpose of orienting the at least one lens about at least one orientation axis, or the drive means comprise a control which is able and adapted to orient the at least one lens in at least substantially continuous and at least substantially optimal manner relative to an actual position of the sun. It will therefore be apparent that the present invention also relates to a device for collecting solar energy comprising collector means and lens means for concentrating solar radiation onto the collector means, wherein the collector means are coupled to an energy processing unit via a light conductor, which is able and adapted to capture and conduct light, wherein a first outer end of the light conductor is coupled to the energy processing unit and the collector means comprise an opposite open outer end of the light conductor.

A further preferred embodiment of the device according to the invention has the feature that the light conductor comprises a glass fibre cable provided on the opposite outer end with an anti-reflection coating. A glass fibre cable in which a set of fibres are for instance brought together or melted together can transport a large quantity of concentrated sunlight with negligible loss of light. By providing the cable on the opposite outer end with an anti-reflection coating a possible loss of light through reflection can be reduced still further, so that a substantially maximum quantity of sunlight passing through the lens means is captured in the cable and conducted to the energy processing unit.

A further preferred embodiment of the device according to the invention has the feature that the energy processing unit comprises a heat accumulator. A relatively large quantity of heat can be stored in the accumulator. Energy can thus be obtained constantly from thus stored heat, and the stored heat can moreover serve as energy buffer when a quantity of collected solar energy is temporarily relatively low.

In a particular embodiment the device according to the invention is characterized in that the accumulator comprises a thermally insulated heat block. Heat can be stored for a relatively long time in such an accumulator without, or with substantially no, loss of heat. In a further particular embodiment the device according to the invention is characterized in that the heat block comprises a thermally conducting core, in particular a copper core. Copper is a particularly good conductive material which is highly suitable for distributing heat provided thereto uniformly over the heat block, thus preventing local heat fluctuations occurring in the heat block which can have an adverse effect on energy yield. In another particular embodiment the device according to the invention is characterized in that the accumulator comprises a thermally insulated storage container with a liquid. Such a storage container is also highly suitable as accumulator for storage of heat therein.

A further preferred embodiment of the device according to the invention has the feature that the lens means comprise a lens system of individual lenses. By applying a plurality of smaller lenses instead of one larger lens, a thickness dimension of the device can be kept small. Lenses of a smaller diameter generally also have a smaller focal distance. If the device has a small thickness dimension, a modular construction thereof for instance becomes possible. Storage, transport and placing of the device are thus made easier. On the other hand, carrying and handling of the device is facilitated by the small thickness dimension thereof.

A particular embodiment of the device according to the invention has the feature that at least a number of lenses of the lens system are arranged on a shared carrier body, and that the carrier body is rectangular with a length and a width of between 80 and 120 cm. The device can thus be handled easily, for instance as a modular unit.

An embodiment of the device according to the invention has the feature that the lenses are disposed rigidly relative to the carrier body, that the carrier body is suspended movably and that the drive means engage on the carrier body and are able and adapted to orient the carrier body subject to the actual position of the sun. The lenses are thus oriented as a result of the orienting of the carrier body. Because the lenses do not each have to be oriented individually, but only the carrier body instead, the drive means and the control can take a relatively simple form.

An alternative embodiment of the device according to the invention has the feature that at least a set of lenses are suspended for rotation about at least a primary rotation axis, that the drive means are able and adapted to rotate the set of lenses in a first direction about the primary rotation axis relative to the carrier body, that the carrier body is suspended for rotation about at least a second rotation axis and that the drive means are able and adapted to rotate the carrier body in a second direction about the secondary rotation axis. By rotating the lenses in the first direction and the carrier body in the second direction it becomes possible to adapt the orientation of the lenses in order to follow a path of the sun.

A particular embodiment of the device according to the invention herein has the feature that the primary and secondary rotation axis are at least substantially perpendicular to each other.

A further preferred embodiment of the device according to the invention has the feature that the lenses are disposed in rows, wherein the lenses of a row are each rotatable about their own rotation axis relative to the carrier body, and wherein the lenses of the row are coupled to an operating arm in order to rotate the lenses of the row together relative to the carrier body. Each row of lenses can thus be provided with its own operating arm, wherein the operating arms are for instance operated together.

Yet another alternative embodiment of the device according to the invention has the feature that the drive means comprise per lens at least a first rotation axis for the purpose of rotating the lens in one direction, and a second rotation axis for the purpose of rotating the lens in another direction, wherein the first and second rotation axes are preferably at least substantially perpendicular to each other. In this embodiment a carrier body for the lenses is stationary. The lenses can nevertheless follow the path of the sun by rotating the lenses about their respective first and second rotation axes. Because the carrier body itself does not move, it can be integrated into for instance a roof, so that the appearance of the roof is not greatly impaired.

A preferred embodiment of the device according to the invention has the feature that the lenses of a row are each rotatable about their own first rotation axis, and wherein the lenses of the row are rotatable about a shared second rotation axis. A further preferred embodiment of the device according to the invention herein has the feature that the lenses of the row are coupled to an operating arm for the purpose of rotating the lenses of the row together about their primary rotation axes. Each row of lenses can thus be provided with its own operating arm, wherein the operating arms are for instance operated together.

A particular embodiment of the device according to the invention has the feature that the wall part has an at least substantially concave progression and that the conduit and the lenses of the row can be rotated together about the second rotation axis. As a result of the concave progression of the wall part of the conduit solar radiation passing through the lenses will on the one hand thus remain concentrated on the collector conduit when the lenses are rotated about their own first rotation axes. As a result of the co-rotation of the conduit with the lenses about the second rotation axis solar radiation passing through the lenses will on the other hand thus also remain concentrated on the collector conduit. Solar radiation passing through the lenses is thus incident on instead of adjacently of the collector conduit in any position of the sun.

A particular embodiment of the device according to the invention has the feature that the lenses have a diameter between 6 and 12 cm. A further particular embodiment of the device according to the invention has the feature that the lenses of the system are directed at shared collector means.

A further preferred embodiment of the device according to the invention has the feature that solar radiation passing through the lens means is concentrated directly onto the collector means. Because the solar radiation is concentrated directly onto the collector means, a mirror is not required to concentrate solar radiation passing through the lens means onto the collector means. The construction of the device can hereby remain simple, and a thickness dimension of the device can remain limited.

The invention will now be further elucidated on the basis of several exemplary embodiments and an accompanying drawing. In the drawing:

FIGS. 1A,B show respectively a top view and a perspective view of a first exemplary embodiment of a device according to the invention;

FIG. 2A is a perspective view of a second exemplary embodiment of a device according to the invention;

FIG. 2B is a side view in more detail of a lens arrangement of the exemplary embodiment shown in FIG. 2A;

FIG. 3A is a perspective view of a third exemplary embodiment of a device according to the invention;

FIGS. 3B,C show in detail a top view and a side view of a lens arrangement of the exemplary embodiment of FIG. 3A;

FIG. 4 shows a first device according to the invention incorporated in an installation for generating steam;

FIG. 5 shows a second device according to the invention incorporated in an installation for generating steam.

The figures are otherwise purely schematic and not drawn to scale. Some dimensions in particular are (highly) exaggerated for the sake of clarity. Corresponding parts are designated as far as possible in the figures with the same reference numerals.

The device 1 shown in FIGS. 1A,B for collecting solar energy comprises a number of individual lenses (lens means) 2 for concentrating solar radiation onto a liquid conduit (collector means) 3 with an inlet 4 and an outlet 5. A thermal oil is applied as liquid. Lenses 2 have a diameter of 8 to 10 cm, are manufactured from glass and can withstand a temperature of more than 1000° C. Liquid conduit 3 is able and adapted to enter into heat-exchanging contact with the oil. Liquid conduit 3 extends successively in a meander pattern along all lenses of device 1. Lenses 2 are mounted in rigid manner on a carrier body 6, wherein carrier body 6 is rotatable about a first rotation axis 7 and a second rotation axis 8 which are mutually perpendicular. Drive means with a control are provided for the purpose of orienting carrier body 6 by rotation about the first and second rotation axes 7,8 for a continuous, optimum orientation of lenses 2 relative to an actual position of the sun, wherein solar radiation is incident perpendicularly on lenses 2. Lenses 2 thus co-rotate with the sun.

The second exemplary embodiment of a device 20 according to the invention shown in FIGS. 2A,B likewise has a carrier body 6 with a number of individual lenses 2. Lenses 2 are however now rotatable in a first direction relative to carrier body 6 around respective primary rotation axes 9. An operating arm 10 is disposed for this purpose along each row of lenses 2 in order to rotate the lenses 2 of the row together relative to carrier body 6. Carrier body 6 is rotatable in a second direction around a secondary rotation axis 11, wherein the primary rotation axes 9 and the secondary rotation axis 11 are mutually perpendicular. By rotating lenses 2 in the first direction and carrier body 6 in the second direction it becomes possible to adjust the orientation of lenses 2 for the purpose of following a path of the sun. Liquid conduit 3 has a curved progression at the position of lenses 2 so that when lenses 2 are reoriented solar radiation passing through lenses 2 remains concentrated on liquid conduit 3. This avoids radiation from the sun being incident adjacently of instead of on liquid conduit 3 as the sun moves. The efficiency of device 20 is thus further increased.

FIGS. 3B,C show in detail a top view and a side view of a number of lenses 2 of a third exemplary embodiment of a device 40 according to the invention shown in FIG. 3A. Device 40 likewise comprises a plurality of lenses 2 which are disposed in rows and provided on a carrier body 6. Carrier body 6 now however has a stationary disposition. As in the exemplary embodiment shown in FIG. 2B, lenses 2 are rotatable relative to carrier body 6 in a first direction around respective primary rotation axes 9 using an operating arm 10 provided for each row. In addition, lenses 2 are rotatable relative to carrier body 6 in a second direction around a secondary rotation axis 12 which is the same for each row of lenses. Lenses 2 herein rotate together with liquid conduit 3 around the secondary rotation axis 12, wherein liquid conduit 3 is mounted for rotation in support elements 13. Liquid conduits 3 are provided at their outer ends with rubber hoses 16 so that liquid conduits 3 can rotate freely. Owing to the rotatability of lenses 2 around the mutually perpendicular primary and secondary rotation axis, lenses 2 can co-rotate with a path of the sun.

When lenses 2 are reoriented, solar radiation passing through lenses 2 will remain concentrated/focused on liquid conduit 3. This is due on the one hand to the curved progression of liquid conduit 3 at the position of lenses 2. This is due on the other hand to the liquid conduit 3 co-rotating around a secondary rotation axis 12 when a row of lenses 2 rotates about secondary rotation axis 12.

The dimensions of carrier body 6 of FIGS. 1, 2 and 3 amount to about 100 cm×100 cm, and 10 rows of lenses, each having 10 individual lenses 2, are disposed on carrier body 6. Regulating means (not shown) are provided for regulating a temperature of the oil at outlet 5 of liquid conduit 3 to about 450° C. The heat of the oil at such a high temperature allows of easy conversion, so that high energy efficiencies can be achieved with the device according to the invention. The applied oil has a boiling point of 500° C. or higher at atmospheric pressure, so that it will not begin to boil.

A possible application of a first device according to the invention is shown schematically in FIG. 4. A liquid conduit 13 forms part of a closed circuit with one storage vessel 14 for the oil. A pump 17 is provided to cause circulation of the oil in liquid conduit 13. Using hot oil in storage vessel 14 with a temperature of about 450° C. steam is generated with which a steam turbine generator set 15 is driven. With a sufficiently large dimensioning of the device according to the invention and storage vessel 14, so much hot oil can be stored in storage vessel 14 that steam and electricity can be generated for longer periods of time. An excess of generated electricity can for instance be supplied to the electricity grid. The thermal oil stored in storage vessel 14 can remain hot for a long time by properly insulating storage vessel 14. Energy stored in storage vessel 14 during periods with much solar radiation can thus be used in periods when there is less solar radiation. The device according to the invention can be applied as individual energy provision for a dwelling, a commercial premises or an industrial estate. An application as district heating is also possible. Yet another application is in the making of hydrogen gas, for instance as fuel for vehicles.

A possible application of a second device according to the invention is shown schematically in FIG. 5. A set of lenses 2 concentrates sunlight onto an open outer end 19 of a light conductor 20 which is coupled with an opposite first outer end to an energy processing unit 23. The sunlight in light conductor 20 is thus captured and transported to energy processing unit 23. Light conductor 20 herein comprises as glass fibre cable a set of glass fibres 21, at least one for each lens 2, which come together in a tube 22 and are guided therethrough to energy processing unit 23. Glass fibres 21 are provided at the open outer end 19 with an anti-reflection coating for the purpose of preventing sunlight passing through lenses 2 from being reflected onto outer end 19. A substantially maximum quantity of the sunlight will hereby be captured in glass fibres 21. Energy processing unit 23 comprises a thermally insulated heat block as heat accumulator. Heat block 23 comprises a copper core 24 to which light conductor 20 is coupled with the first outer end. Copper core 24 conducts heat from the captured sunlight to a metal sheath in which the heat is stored. Heat block 23 is thermally insulated with a layer of insulation material, for instance of needle felt. By connecting a heat exchanger to the metal sheath, steam can easily be generated with which a steam turbine generator set 15 is driven. This second device according to the invention thus provides for a relatively sustained generation of steam and electricity from sunlight.

Although the invention has been further elucidated only on the basis of several exemplary embodiments, it will be apparent that the invention is by no means limited thereto. On the contrary, many more variations and embodiments are possible for the person with ordinary skill in the art within the scope of the invention. A skilled person will thus appreciate per se the advantages of a device with a light conductor for the purpose of transporting sunlight to an energy processing unit, even without the movable lens means according to the invention. The invention therefore also relates as such to a device for collecting solar energy, comprising collector means and lens means for concentrating solar radiation onto the collector means, wherein the collector means are coupled to an energy processing unit via a light conductor able and adapted to capture and conduct light, wherein a first outer end of the light conductor is coupled to the energy processing unit and the collector means comprise an opposite open outer end of the light conductor. 

1. Device for collecting solar energy, comprising collector means and lens means for concentrating solar radiation onto the collector means, wherein the collector means are coupled via a conduit for energy transport to an energy processing unit, characterized in that the lens means are arranged movably and comprise at least one lens, that drive means are provided to orient the at least one lens about at least one orientation axis and that the drive means are provided with a control for the purpose of orienting the at least one lens in at least substantially continuous and in at least substantially optimal manner relative to an actual position of the sun.
 2. Device as claimed in claim 1, characterized in that the conduit comprises a liquid conduit for carrying a liquid therethrough, that the collector means comprise at least a wall part of the liquid conduit, and that the wall part is able and adapted to enter into heat-exchanging contact with the liquid.
 3. Device as claimed in claim 2, characterized in that the wall part has an at least substantially concave progression.
 4. Device as claimed in claim 2, characterized in that regulating means are provided to regulate a liquid temperature to a value between 400 and 500° C., preferably to about 450° C.
 5. Device as claimed in claim 1, characterized in that the conduit comprises a light conductor which is able and adapted to capture and conduct light, wherein a first outer end of the light conductor is coupled to an energy processing unit and the collector means comprise an opposite open outer end of the light conductor.
 6. Device as claimed in claim 5, characterized in that the light conductor comprises at least one fibre, in particular a glass fibre.
 7. Device as claimed in claim 6, characterized in that the light conductor comprises a glass fibre cable provided on the opposite outer end with an anti-reflection coating.
 8. Device as claimed in claim 1, characterized in that the energy processing unit comprises a heat accumulator.
 9. Device as claimed in claim 8, characterized in that the accumulator comprises a thermally insulated heat block.
 10. Device as claimed in claim 9, characterized in that the heat block comprises a thermally conducting core, in particular a copper core.
 11. Device as claimed in claim 8, characterized in that the accumulator comprises a thermally insulated storage container with a liquid.
 12. Device as claimed in claim 1, characterized in that the lens means comprise a lens system of individual lenses.
 13. Device as claimed in claim 12, characterized in that at least a number of lenses of the lens system are arranged on a shared carrier body.
 14. Device as claimed in claim 13, characterized in that the carrier body is rectangular with a length and a width of between 80 and 120 cm.
 15. Device as claimed in claim 13, characterized in that the lenses are disposed rigidly relative to the carrier body, that the carrier body is suspended movably and that the drive means engage on the carrier body and are able and adapted to orient the carrier body subject to the actual position of the sun.
 16. Device as claimed in claim 13, characterized in that at least a set of lenses are suspended for rotation about at least a primary rotation axis, that the drive means are able and adapted to rotate the set of lenses in a first direction about the primary rotation axis relative to the carrier body, that the carrier body is suspended for rotation about at least a second rotation axis and that the drive means are able and adapted to rotate the carrier body in a second direction about the secondary rotation axis.
 17. Device as claimed in claim 16, characterized in that the primary and secondary rotation axis are at least substantially perpendicular to each other.
 18. Device as claimed in claim 16, characterized in that the lenses are disposed in rows, wherein the lenses of a row are each rotatable about their own rotation axis relative to the carrier body, and wherein the lenses of the row are coupled to an operating arm in order to rotate the lenses of the row together relative to the carrier body.
 19. Device as claimed in claim 13, characterized in that the drive means comprise per lens at least a first rotation axis for the purpose of rotating the lens in one direction, and a second rotation axis for the purpose of rotating the lens in another direction, wherein the first and second rotation axes are preferably at least substantially perpendicular to each other.
 20. Device as claimed in claim 19, characterized in that the lenses of a row are each rotatable about their own first rotation axis, and wherein the lenses of the row are rotatable about a shared second rotation axis.
 21. Device as claimed in claim 20, characterized in that the lenses of the row are coupled to an operating arm for the purpose of rotating the lenses of the row together about their own first rotation axes.
 22. Device as claimed in claim 2, characterized in that the lenses have a diameter between 6 and 12 cm.
 23. Device as claimed in claim 2, characterized in that the lenses of the system are directed at shared collector means.
 24. Device as claimed in claim 1, characterized in that solar radiation passing through the lens means is concentrated directly onto the collector means. 